Recently, a secondary battery, which can be charged and discharged, has been widely used as an energy source for wireless mobile devices. Also, the secondary battery has attracted considerable attention as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles using fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle- or large-sized devices, such as vehicles, use a middle- or large-sized battery module having a plurality of battery cells electrically connected to one another because high power and large capacity are necessary for the middle- or large-sized devices.
Generally, a battery module is manufactured by placing a plurality of unit cells in a cartridge in a state in which the unit cells are connected in series and/or parallel to one another and electrically interconnecting the plurality of cartridges. According to circumstances, a middle- or large-sized battery pack or system having two or more battery modules electrically connected to each other is manufactured to provide higher power.
Consequently, the connection between electrode terminals is needed for electrical connection between batteries (including unit cells), battery cartridges, or battery modules and for connection of the batteries, the battery cartridges, or the battery modules to an external device to which power will be supplied from the batteries, the battery cartridges, or the battery modules.
However, electrode terminal connection regions have a high likelihood of short circuiting when external impact is applied to the electrode terminal connection regions. Furthermore, high voltage flows in the electrode terminal connection regions. Consequently, attention must be paid to the electrode terminal connection regions during work or use.
For example, for a middle- or large-sized battery pack mounted in an electric vehicle or a hybrid electric vehicle, a pack case of the battery pack is made of a metal material which provides desired mechanical strength to the pack case. Consequently, when external impact, for example due to a car collision, is applied to the middle- or large-sized battery pack, the pack case is deformed, with the result that the pack case may come into contact with electrode terminal connection regions of battery modules, whereby short circuits may occur.
In order to solve this problem, some prior arts suggest a method of arranging the electrode terminal connection regions of the battery module in the lateral direction of a vehicle, not in the frontward-and-backward direction of the vehicle having a great possibility of collision or a method of providing an extra space for impact alleviation at the front of the battery module when the electrode terminal connection regions of the battery module are arranged in the frontward-and-backward direction of the vehicle. However, the above-suggested technologies have a problem in that arrangement efficiency of the battery module in a device is greatly deteriorated.
In connection with this matter, some of the prior arts suggest a battery module constructed in a structure in which electrode terminal connection regions are closed by protection covers. For example, Japanese Patent Application Publication No. 2006-228706 discloses a battery module including a bus bar for electrically inter-connecting adjacent batteries, an electrically insulative side plate for supporting the bus bar, a coupling member for coupling the bus bar to output terminals disposed at sides of the batteries, and an electrically insulative protection cover for closing the side plate, the protection cover having an opening through which the coupling member is inserted.
However, the protection cover of the disclosure is not provided with an additional member for impact alleviation. As a result, the protection cover has problems in that the protection cover may not protect the connection regions when external impact is applied, and therefore, it is not possible to fundamentally prevent the occurrence of a short circuit and thus the occurrence of a fire.
Consequently, there is a high necessity for an electrode terminal connecting device that is capable of fundamentally solving the above problems, effectively achieving electrical connection between battery modules, isolating electrode terminal connection regions from the outside, and alleviating external impact when the external impact is applied.